Merge branch '1842-correct-the-bind-arm-to-say-that-the-default-session-key-for-use-with-update-policy-local-is' into 'master'
Resolve "Correct the BIND ARM to say that the default session-key for use with 'update-policy local;' is generated at startup"
Closes #1842
See merge request !3664

We were passing client address to dns_resolver_createfetch as a pointer
and it was saved as a pointer. The client (with its address) could be
gone before the fetch is finished, and in a very odd scenario
log_formerr would call isc_sockaddr_format() which first checks if the
address family is valid (and at this point it still is), then the
sockaddr is cleared, and then isc_netaddr_fromsockaddr is called which
fails an assertion as the address family is now invalid.

Make various adjustments necessary to enable "make dist" to build a BIND
source tarball whose contents are complete enough to build binaries, run
unit & system tests, and generate documentation on Unix systems.
Known outstanding issues:
- "make distcheck" does not work yet.
- Tests do not work for out-of-tree source-tarball-based builds.
- Source tarballs are not complete enough for building on Windows.
All of the above will be addressed in due course.

Merge lib/isc/unix/ifiter_getifaddrs.c into lib/isc/unix/interfaceiter.c
and lib/isc/xoshiro128starstar.c into lib/isc/random.c. This avoids the
need for extra Automake directives required to process the "helper" *.c
files properly and makes the code more localized.

Turn the static check_bad_bits() function used by both Unix and Windows
systems into a "private" function and extract the "private" parts of
lib/isc/fsaccess.c to lib/isc/fsaccess_common_p.h. Instead of including
lib/isc/fsaccess.c from lib/isc/{unix,win32}/fsaccess.c, make the former
an independent C source file.
Rename lib/isc/fsaccess.c to lib/isc/fsaccess_common.c to prevent build
issues on Windows caused by multiple source files (lib/isc/fsaccess.c,
lib/isc/win32/fsaccess.c) being compiled into the same object file.
These changes improve consistency with the way "private" functions and
macros are treated elsewhere in the source tree.

DS records only belong at delegation points and if present
at the zone apex are invariably the result of administrative
errors. Additionally they can't be queried for with modern
resolvers as the parent servers will be queried.

When ./run.sh <test> is invoked, it acts as a wrapper around
`env - TESTS="<test>" make -e check` to preserve the ability to build
files defined only in the `check` target. Unfortunately, cleaning the
full environment had a side-effect of some tests failing due to missing
binaries and libraries. We now preserve the two most important
variables - PATH and LD_LIBRARY_PATH.

Various SoftHSM versions differ in algorithm support. Since Fedora
tends to have the latest SoftHSM version available in its stock package
repositories, enable PKCS#11 support in Fedora jobs to test multiple
SoftHSM versions in GitLab CI.